The present invention relates to electrical apparatuses, etc. enabled to connect such a power source as an AC adapter, etc. and a battery that charges, then discharges to power a subject. More particularly, the present invention relates to electrical apparatuses, etc. enabled to be powered by both of such a power source as an AC adapter, etc. and a battery.
In addition to a commercial power source that supplies a power directly, batteries (power accumulators, secondary batteries, and primary batteries) that can be used limitless by repeating charging and discharging are employed to power information terminals represented by lap-top personal computers (PCs), such personal devices as PDA (Personal Digital Assistant), and various kinds of electrical apparatuses as portable audio devices, video cameras, etc. Nickel hydrogen batteries (NiMH batteries) and nickel cadmium batteries (Ni—Cd batteries) that are comparatively large in capacity and low in price are employed as such batteries. There are also other types of batteries such as lithium ion batteries that are higher in energy density per unit weight than the nickel cadmium batteries, as well as lithium polymer batteries that use solid polymer without using the liquid electrolyte.
FIG. 7 shows a typical circuit diagram of a conventional lap-top PC. In this PC, an AC adapter 501 connected to a commercial power source and enabled to supply a power and a battery 502 that charges, then discharge to supply a power are connected to a body side of the PC respectively. At this body side, subcircuits #1 to #5 are connected to each of the power supplies directly or via a DC/DC converter 505 and a DC/DC converter 506. In this state, an embedded controller 503 controls the CTRL 1 signal to drive the AC adapter 501 or battery 502 selectively. In other words, when the CTRL 1 signal is turned on, a switch (SW1) is turned on, thereby the AC adapter 501 is connected to the PC body. At this time, because the voltage of the battery 502 is lower than that of the AC adapter 501, the AC adapter 501 powers the PC body. On the other hand, when the CTRL 1 signal is opened (off), the battery 502 begins powering the PC body even while the AC adapter 501 is connected to the PC body. In the conventional circuit configuration, the PC is driven by the AC adapter 501 and the battery 502 only in two operation modes, one of which is selected according to the circumstances.
Furthermore, “peak shifting” has also been required in recent years to reduce the peak power consumption in a time zone in which the power consumption rises extremely, for example, in the afternoon in summer due to concurrent operations of coolers. Power companies are also required urgently to increase the capital investment for leveling the power load as much as possible so as to cope with this peak power consumption. One of the “peak shifting” methods is as follows. The electrical apparatus is configured so as to be powered only from the battery 502 while power supply from commercial source via the AC adapter 501 stops in such a much power consuming time zone (for example, for three hours from 1 p.m. to 4 p.m.), thereby such the peak time power consumption will be more reduced.
However, when how lap-top PCs are used is checked, it has been found that the capacity of the battery 502 is often used up in one hour or so. And, after the battery 502 is used up, the PC is powered by the AC adapter 501, so that the peak power consumption can be reduced effectively only for one hour from 1 p.m. to 2 p.m.
In the case where such the power reduction effect cannot be continued up to a desired time zone, one of the effective methods to solve such the problem is a power management function to be executed for lowering the CPU operation speed at the body side and the brightness of the liquid crystal display (LCD). However, this method has another problem, that is to say, lowering the CPU operation speed and the LCD brightness often causes the user to be disappointed at the performance of the PC in specific utilization. In addition, the conventional power management function is insufficient to lower the power, so that the operating time of the battery 502 cannot be extended so long.
Under such circumstances, it is an purpose of the present invention to optimize the power consumption of both a power supply connected to a commercial power source and a battery so as to solve the above described conventional technical problems.
It is another purpose of the present invention to provide an electrical apparatus configured by optimizing the power consumption of each power source and giving consideration to environmental and power problems.